Types Of Weathering Flashcards
Salt crystal growth
Caused by crystallisation of salt within rocks.
High temps draw out saline ground water to the surface.
Evaporation leaves behind salt.
Expansion of crystals creates stresses in the rocks/cracks.
Major cause of weathering in deserts, and porous sedimentary rocks like sandstone.
Block Disintegration
Caused by heat and cooling of well-jointed rocks like limestone.
Rocks break down along joins and bedding, as they are weakest points.
Granular Disintegration
Desert temps range from freezing to 40C.
Causing rock surfaces to expand and contract resulting in mechanical fracture.
Known as insolation weathering.
Define Weathering
Weathering is the decay and disintegration of rocks insitu involving physical, chemical and biological processes.
Excludes erosional effects.
Freeze-Thaw weathering
Water trapped in confined cracks and spaces within rocks.
Expanding 9% of its volume when freezing.
Pressure exerted by the ice causes the rock the fracture and crack.
Only in conditions with moisture and temps fluctuating below freezing.
Vegetation Rock action
Biological weathering is either chemical or physical.
Simply breaking of rocks etc by animals.
E.g. Rocks fractured by burrowing animals/by roots of trees.
Organisms producing chemicals that decompose chemicals.
Pressure release (Dialation)
Majority of igneous rocks are created in mantel at high temps.
Erosion of lithosphere places rocks below under less pressure.
The rocks below are pushed to the surface causing fractures etc.
Hydration and Dehydration
Causes addition or removal of water in minerals.
Causing expansion or contraction which assists in disintegration.
Hydrolysis
Minerals being broken down via reactions with water.
Usually occurs in acidic conditions.
Carbonation
Carbonic acid absorbs CO2 in the atmos to become acid rain.
Dissolves limestone.
